Maintaining the stability of a payload being transported suspended from an aircraft during flight provides a number of challenges. Some approaches to the challenges associated with suspended payload stabilization include rear attached fins, kite tails and dynamic stabilization. However, these systems tend to be large and bulky. In some cases, these systems become a permanent fixture to the payloads, which can reduce the performance of the item when in use.
In helicopter lifting applications, helicopters are used to lift equipment and transport the equipment to locations not easily accessible by crane or land vehicles. As the helicopter moves to that location, the payload must be stable so as to not endanger the aircrew, ground crew, bystanders or the equipment. A stable payload equates to a safer work environment, shorter transportation time and longer aircraft range. A more stable payload reduces operational costs and increases the distances a payload may be transported without refueling.
Fins that are used in payload stabilization are traditionally made from various types of rigid materials and are located on the rear of the payload. When on the rear of the payload, the fin tends to be behind the point of rotation of the payload. This keeps the payload oriented in parallel with the airflow and increases the stability. However, to increase effectiveness the fin is required to be secured permanently to the payload. When the fin is designed as a permanent structure to the payload, the fin or stability equipment cannot be moved from one payload to another and restricts flexibility. A permanent fin system can also prevent the load from conducting its primary purpose.
The fins must also be placed on the payload in such a manner that the fins interact with the free stream airflow. In some instances of this type of configuration, the payload may block some of the air and create turbulence, reducing the effectiveness of the fin system.
Kite tails or streamers can be secured to the rear of the payload to stabilize the payload or equipment. However, the disadvantages of this approach include the kite tail or streamer becoming entangled with the aircraft equipment, which can include for example, the rotor blades of a helicopter. To prevent the streamer from contacting the rotor blades, the streamer is typically constructed of a heavy chain and a large heavy item is secured to the end. This increases the weight of the system and decreases the performance characteristics of the aircraft.
Dynamic stabilization requires complex and bulky electronics with high powered computing systems to monitor the payload movement and provide a stabilizing force to counteract the moving force. These dynamic systems tend to be power intensive and require a significant amount of calibration for the complex instrumentation. The cost to use and maintain this type of system can be extensive, depending upon the size of the payload and the expected restoring forces required to be generated.
Accordingly, it would be desirable to provide a suspended payload stability device that addresses at least some of the problems identified above.